Oxygen breathing system



J. R. JOHNSON, JR

OXYGEN BREATHING SYSTEM 2 SHEETS-SHEET l May 13, 1952 Filed March 30, 1951 BEE/7mm? .sw/reH 3Z\ V I 34 f-Zow #ypmmve flssemaLy 0x YGE/V SUFFY 97708 NE Y5 May 13, 1952 Filed March 30 1951 J. R. JOHNSON, JR 2,596,152 OXYGEN BREATHING SYSTEM 2 SHEETSSHEET 2 JOHN E. .JO/Y/VJO LIE.

wue; 8ND ZZ/MWKK Patented May 13, 1952 UNITED STATES PATENT OFFICE (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 7 Claims.

The invention described herein may be manufactured and used by or for the United States Government for governmental purposes without payment to me of any royalty thereon.

This invention relates to oxygen breathing systems and especially to a signaling device which becomes automatically operative to warn a pilot or a crew member of a lack of oxygen being supplied him.

The invention essentially comprises a simple, compact and enicient signaling mechanism which may be contained in a conventional oxygen regutained in a case which is only 1% long by 1 diameter, whereby space may be found for the device within the regulator itself.

Inasmuch as the flow indicator assembly of the regulator may include the on and off switch operable by flow through the regulator, this switch may be employed to open or close the circuit of the signaling device.

In the drawings which illustrate several embodiments of subject invention:

Fig. 1 is a schematic view of an embodiment of the invention showing the bi-metal switch contact strips, the heating coils, the wiring, and the contacts.

Fig. 2 is a schematic view of an improved ver= sion of the invention shown in Fig. 1.

The mechanism which isthe subject of this invention consists of a body I which contains two bimetal strips I2 and I4, strip I 2 being straight and strip I4 being of fishhook contour I6 at the free end. The outer ends of strips I2 and I4 are insulatedly attached to the body It.

v Silver contacts I8 and 20 are electrically connected ,to the hook end I of the bimetal strip I4. -Silver contacts 22 are electrically connected to the free end of the straight strip I2. Re sistance ,wireheating coils 24 and 25 surround bimetal strips I2 and I 4, respectively. A signal light 28 is connected into the circuit as shown.

Signal light 28 is preferably not carried on or in the body It but is mounted on a control panel 3D in the pilots compartment. Additional lights 28 (not shown) may be provided, one for each crew member, and should be connected in series so that the system may not be put into operation 2 unless the pilotand all crew members have their lights turned on.

A pneumatically actuated breathing switch 32, which, for clearness, in Figs. 1 and 2, is shown outside the flow indicator assembly, is, in actual practice, containedwithin and made a part of said assembly. Switch 32 is shown open. It is pneumatically actuated to open or closed position. by the breathing pulsations of the user. A manually actuable master switch 36 is provided to disconnect the device from the power source 33. Switch 38 is shown as part of the circuit diagram Figs. 1 and 2, although in practice it is contained within the regulator. A manually actuable switch 40 is provided for clearing the circuit after the device has operated.

The operation of the switch mechanism shown in Fig. lis as follows:

When the master switch 36 is closed, as shown, and breathing begins, current will flow from the current source 38 through the heating coils 24 and 25. As the breathing switch 32 opens and closes the current in the heating coil 24 will be relatively strong but pulsating, while the current in the heating coil 25 is relatively weak but steady, thereby providing a steady but relatively dim light in lamp 28. The resistance of heating coils 24 and 2'6 is so proportioned that bimetal strips I2 and I4 warp in the direction of the arrows 45 and 48 substantially equal amounts and in consequence the contact 29 does not engage the co-ntact22 at this time, i. e., the stronger but pulsating current in coil24 balances the weaker but steady current in coil 26 in warping their respective bimetals substantially equal amounts in the direction of the arrows 48 and 46.

If now, from any. cause, the device malfunctions so that the breathing switch 32 remains open for a longer period than it does in normal breathing, there will be no current flowing through heating coil 24 whereby thebimetal strip l2 returns to its straight condition while the current through the heating coil 26 will Warp the bimetal strip I4 upward bringing contact 25, into engagement with contact 22.

When the contact 23 engages the contact 22, the current flows from the source 38 through bimetal strips I4 and I2 and through the lamp 28 thereby shorting out the heating coil 26. No current is now passing through either heating coil 24 or 26, whereby the bimetal strip I2 maintains its straight outline, while the warped part of bimetal strip I4 straightens and withdraws contact 20 from contact 22 which again forces current to flow through the heating coil 26. This 3 cycle is repeated as long as the breathing switch 32 is open by reason of the malfunctioning of its operating means, whereby the lamp 23 is fairly bright but blinking.

On the other hand, the device may malfunction with the breathing switch in the closed position for a longer period than it remains closed during normal operation. In such a situation the current will flow through the heating coil 24 and warp the bimetal strip I2 upward and will flow through the heating coil 26 and warp the bimetal strip 14 upward. Due to the fact that, in this case, the flow is continuous in coil 24 and not intermittent as in normal operation, the heating of coil 24 will be greater than in normal operation and the resultant deflection of the strip l2 will exceed the deflection of the strip l4 by an amount sufiicient to engage contact 22 with the contact 18. When this occurs the heating coil 26 is shorted out and the light 28 is connected directly across the current source 38 through the contacts l8 and 22 thus giving a continuous bright warning light.

Now since the breathing switch 32 is closed, the current will flow through the heating coil 24 whereby the bimetal I2 will be warped in the direction of the arrow 48, and since the coil 26 will be shorted out, the bimetal strip 14 will attempt to assume its straight position but cannot do so because the contact I8 will be resting on the contact 22.

In order to now permit the device to return to normal, i. e., to permit the bimetals I2 and M to straighten and separate the contacts 18 and 22 as seen in Fig. l, the coil 24 must be shorted out, and this may be done by manually holding the breathing switch 32 open for a sufficient time to allow the coil 24 to cool or, what is preferable, by providing the additional switch 40 which may be opened and left open until the coil 24 cools and restores the device to normal.

The main fault in the device shown in 1 is the requirement of a separately operable manual switch to clear the circuit after pressure breathing, the condition whereunder a malfunc tioning switch 32 would remain in the closed position, has been in effect.

Some of the advantages of the foregoing system as shown in Fig. 1 are (1) It alleviates, in part, the confusion of periodic interphone oxygen checks although these are still recommended at convenient intervals.

(2) The steady dim light of the system establishes confidence that the system is operating.

(3) The system is simple, compact and requires very little technical maintenance.

(4) The system is simple to construct and install.

The disadvantages above pointed out are completely cured in the modifications shown in Fig. 2.

Referring more particularly to Fig. 2, the body In contains three bimetal strips [2, l3 and I5, all normally straight when the device is not operating. The outer ends of strips [2, l3 and IS-are insulatedly attached to the inside of the casing H3.

Silver contacts l8, Eli and 22 are carried on and in electrical communication with the free ends of the bimetal strips l5, l3 and I2, respectively. Resistance wire heating coils 24 and 26 surround bimetal strips [2 and I3, respectively. Associated with each signaling device, Fig. 2, are two signal lamps 28 connected in the circuit in series as shown.

Normally the two signal lights 28 are located one at the crew position and one on a central control panel in the pilots compartment. The several lights on the central control panel had preferably be connected in series on the grounded side of the lamp so that the system may not be put into operation unless all of the crew members and the pilot have their light circuits closed.

The lamps on the panel actually have individual sources of current since each is connected only in series with the individual lamp at the screw position regulator involved.

The pneumatically actuated breathing switch 32 is contained within and is a part of the fiow indicator assembly as it is in the structure shown in Fig. 1. Like the device of Fig. 1 it is pneumatically actuated to open and close in response to the breathing of the user. A manual master switch 36 is provided to disconnect the device from the power source 38. In practice the switch 36 is carried by the regulator. The switch 40. necessary to the exemplification of Fig. 1 is not required in the modification, Fig. 2.

The operation of the modification shown in Fig. 2 is substantially as follows:

When the master switch 35 is closed as shown and normal breathing begins, current will flow from the current source 38 through the heating coils 24 and 28 as it does in the exemplification shown in Fig. 1, i. e., through the coil 24 via the breathing switch 32 when it is open, and through the coil 26 by way of the lamp 28. Since the breathing switch 32 opens and closes with the breathing, the current in the heating coil 24 will pulsate, while the current in the heating coil 26 which is independent of the breathing switch 32 is steady thereby providing a steady light in the lamps 23.

The resistances in the heating coils 24 and26 are so proportioned that a relatively strong but pulsating current passing through the heating coil 24 has about the same effect in warping the bimetal strip i2 as a relatively weaker but steady current, passing through the heating coil 26, has in warping the bimetal strip l3. Bimetal strips l2 and i3 therefore warp substantially equal amounts in the direction of the arrows 48 and 46, respectively, whereby contacts 20 and 22 remain spaced apart substantially as they are when their bimetal strips are straight. Nor is the maximum upward flexing of the bimetal strip [2 sufficient at this time to engage the contact 22 with the contact 18. The lamp 28 therefore burns steady but dim as long as the device is functioning properly, i. e., as long as the breathing switch 32 pulsates and does not tarry too long either in the open or in the closed position.

If for any reason the device now is damaged by enemy fire or if for any other reason it malfunctions, so that the breathing switch 32 remains open for a longer period than it does in normal breathing, there will be no current flowing through heating coil 24 whereby the bimetal strip l2 remains straight while the current through heating coil 25 will warp the bimetal strip 13 in the direction of the arrow 46 thereby bringing contact 22 into engagement with contact 22.

The current will now flow from the source 38 through bimetal strips l3 and I2 and through the lamps 28 thereby shorting out the heating coil 26. With the breathing switch 32 open and the heating coil 26 shorted out, no current will pass through either coil 24 or 26 but will pass through bimetal strips 13 and I2 and through the lamp, burning it brightly.

With no current flowing in heating coil 26 the bimetal strip [3 cools rapidly so that, in a matter -sof seconds, the warped-bimetal strip l3 strightens andiwithdraws itsicontact 2|! from the-contact 22 thusbreaking the circuit=through the-bimetal strips lZand l3 and restoring the circuit through the heating coil 26. 'This cycle, ice. "the alternately blinking first bright then dim cycle is repeatedwhenever the breathing switch 32 re- -mainsopen asshown for aperiod longer than in position'for a longer period than it remains closed during normal breathing. In that case the current willflow-continuously through the -heating coil 24 and warp the bimetal-strip H: in thedirection of the arrow 48, and at the same time current will "flow through the heating coil 26 and warp the bimetal strip l3 in the same direction-as the strip I2 whereby the contacts 20 and 22 remain apart. The bimetal strip l5, however, does not have a heating coil surrounding it and therefore remains straight, so that while the contacts 20 and 22 remain apart, the contact 22 will engage the contact l8.

Current now flows through bimetal strips and I2 and through the lamp 28, giving a corn tinuous bright warning signal.

Whether the warning pertains to demand breathing or to pressure breathing, the system automatically returns to normal operation immediately after the trouble causing the warning is corrected and normal breathing is resumed. This is one of the most valuable features of the modification shown in Fig. 2 over the structure shown in Fig. 1.

I claim:

1. An oxygen want warning device which comprises, a switch body, two spaced apart bimetal strips having one end insulatedly supported by said body, a third bimetal strip having one end insulatedly supported by said body and the free end extending between the free ends of the said two spaced apart bimetal strips, spaced apart contact points carried on the free ends of said bimetal strips, a heating coil adjacent one of the said two spaced apart bimetal strips, a second heating coil adjacent the said third bimetal strip, an electric warning lamp, a source of electric current supply, and conductors for electrically connecting the said source of current supply to one end of the first mentioned heating coil; for electrically connecting the other end of the first mentioned heating coil to said lamp; for clectrically connecting the said source of current supply to one end of the second mentioned heating coil; for electrically connecting the other end of the said second mentioned heating coil to one end of the flow indicator contacts of an 0xygen regulator; for electrically connecting the said source of current supply to the said two spaced apart bimetal strips, and for electrically connecting the said third bimetal strip to the said lamp.

2. An oxygen want warning device which comprises, a switch body, two spaced apart bimetal strips each having one end insulatedly supported by said body, a third bimetal strip having one end insulatedly supported by said body and the free end extending between the free ends of the said two spaced apart bimetal strips, contact means on the free ends of said bimetal strips positioned upon engagement to bring the first or second bimetal strip into electrical communication with the third bimetal strip, a heating coil surrounding one of the said two spaced apart bimetal strips, ase cond heating; coil surrounding the said third bimetal strip,,an electric warning la p, a source of electric current supply, and. conductors for electrically connecting the saiclsource of current supply to one end of the first mentioned heating coil; for electrically connecting the other end of the first mentioned heating coil to said lamp; for electrically'connecting the said source of current supply to one end of the secondmentioned heating coil; for electrically connecting the other end of the said second mentioned heating coil to one end of the flow indicator contacts ofan oxygen regulator; for electrically connecting the said source of-current supply to the said two. spaced apart bimetal strips, and forelectrically connecting the-said third bimetal strip to the. said lamp.

3. An oxygen want warningdevice which comprises, a switch body, two spaced apart bimetal strips having one end insulatedly supported by said body, a third bimetal strip having one end insulatedly supported by said body and the free end extending between the free ends of the said two spaced apart bimetal strips, spaced apart contact points carried on the free ends of said bimetal strips, a heating coil adjacent one of the said two spaced apart bimetal strips, a second heating coil adjacent the said third bimetal strip, a plurality of electric warning lamps, connected in series, a source of electric current supply, and conductors for electrically connecting the said source of current supply to one end of the first mentioned heating cell; for electrically connecting the other end of the first mentioned heating coil to said lamp; for electrically connecting the said source of current supply to one end of the second mentioned heating coil; for electrically connecting the other end of the said second mentioned heating coil to one end of the flow indicator contacts of an oxygen regulator: for electrically connecting the said source of current supply to the said two spaced apart bimetal strips, and for electrically connecting the said third bimetal strip to one terminal of the first lamp of the series.

4. An oxygen want warning device which comprises, a switch body, two parallel spaced apart bimetal strips having one end insulatedly supported within said body, a third bimetal strip having one" end insulatedly supported within said body and the free end extending between the free ends of the said two parallel spaced apart bimetal strips, spaced apart contact points elec-- trically joined to the free ends of said bimetal strips, a heating coil wound on one of the said two parallel spaced apart bimetal strips, a second heating coil wound on the said third bimetal strip, a series of electric warning lamps, one for each breathing station, a source of electric current supply, and conductors for electrically connecting the said source of current supply to one end of the first mentioned heating coil; for electrically connecting the other end of the first mentioned heating coil to one terminal of the first of the series of said lamps; for electrically connecting the said source of current supply to one end of the second mentioned heating coil: for electrically connecting the other end of the said second mentioned heating coil to one end of the flow indicator contents of an oxygen regulator; for electrically connecting the said source of current supply to the said two spaced apart bimetal strips, and for electrically connectin the said third bimetal strip to one terminal of the first of the series of said lamps.

5. In an oxygen breathing device, an oxygen supply means, an oxygen regulator, an oxygen mask, conduit means connecting the oxygen supply, the regulator and the mask, in combination with a signalling device for indicating when the flow indicator of the regulator is malfunctiom ing, said signalling device comprising three bimetal strips each having one end insulatedly fixed and the free ends provided with spaced apart contacts, a heating coil surrounding the first bimetal strip, a second heating coil surrounding the second bimetal strip, a signal lamp, a breathing switch, a source of electric current, and electrically conductive material joining the said electric current source to the beginnings of the first and the second heating coils, and to the fixed ends of the first and the third bimetal strip, and electrically conductive material joining the fixed end of the second bimetal strip and the end of the first said heating coil to the lamp; and the end of the second said heating coil to the breathing switch.

6. In an oxygen breathing device a signalling means for indicating when the breathing through the device is not normal, said signalling means comprising three bimetal strips each having one end insulatedly fixed and the free ends spaced apart, a heating coil surrounding the first bimetal strip, a second heating coil surrounding the second bimetal strip, a signal lamp, a breathing switch, a source of electric current, and electrically conductive means joining the said electric current source to the beginning of the first and the second heating coils, and to the fixed ends of the first and the third bimetal strips, and electrically conductive means joining the fixed end of the second bimetal strip and the end of the first heating coil to the lamp and the end of the second said heating coil to the breathing switch.

JOHN R. JOHNSON, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Lindsay Jan. 27, 1948 Number 

